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<title>HSF Opcode Definition</title>
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      <H2><FONT color=#0000a0 face="arial,helvetica,sans-serif">TKE_NURBS_Curve</FONT></H2>
      <H3><FONT color=#0000a0 face="arial,helvetica,sans-serif">Opcode</FONT><STRONG><FONT face="arial,helvetica,sans-serif">
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          <TD height=12 width=131>ASCII</TD>
          <TD height=12 width=390>N</TD></TR>
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          <TD height=12 width=131>Hexadecimal</TD>
          <TD height=12 width=390>4E</TD></TR>
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          <TD height=12 width=131>Decimal</TD>
          <TD height=12 width=390>78</TD></TR></TABLE></H3>
      <P>&nbsp;</P></FONT></STRONG>
      <H3><FONT color=#0000a0 face="arial,helvetica,sans-serif">Operands </FONT></H3>
      <P><FONT face="Courier New,Courier,typewriter">
	  <STRONG>Byte</STRONG>&nbsp;options,
	  <STRONG>Byte</STRONG>&nbsp;degree,
	  <STRONG>Long</STRONG>&nbsp;control_count,
      <STRONG>(</STRONG><EM>control_count</EM><STRONG>)xPoint</STRONG>&nbsp;control_points,
      <STRONG>[(</STRONG><EM>control_count</EM><STRONG>)xFloat</STRONG>&nbsp;weights<STRONG>]</STRONG>,<br>
      <STRONG>[(</STRONG><EM>control_count+degree+1</EM><STRONG>)xFloat</STRONG>&nbsp;knots<STRONG>]</STRONG>,<br>
	  <STRONG>[Float</STRONG>&nbsp;start<STRONG>]</STRONG>,
	  <STRONG>[Float</STRONG>&nbsp;end<STRONG>]</STRONG>
	  </FONT></P>

<FONT face="arial,helvetica,sans-serif">	  
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    <TD height=21 width=131>options</TD>
    <TD height=21 width=390>bitmask indicating which options are present</TD>
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    <TD height=21 width=131>degree</TD>
    <TD height=21 width=390>degree of the curve</TD>
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    <TD height=21 width=131>control_count</TD>
    <TD height=21 width=390>number of control points in the curve</TD>
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	<td WIDTH=131 HEIGHT=21>control_points</td>
	<td WIDTH=390 HEIGHT=21><EM>control_count</EM> triplets of x, y, z data</td>
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	<td WIDTH=131 HEIGHT=21>weights</td>
	<td WIDTH=390 HEIGHT=21><EM>control_count</EM> weight factors</td>
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	<td WIDTH=131 HEIGHT=21>knots</td>
	<td WIDTH=390 HEIGHT=21><EM>control_count + degree + 1</EM> knot values</td>
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	<td WIDTH=131 HEIGHT=21>start</td>
	<td WIDTH=390 HEIGHT=21>parametric start point (0-1, default 0)</td>
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	<td WIDTH=131 HEIGHT=21>end</td>
	<td WIDTH=390 HEIGHT=21>parametric end point (0-1, default 1)</td>
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 <P>&nbsp;</P></FONT>

<H3><FONT color=#0000a0 face="arial,helvetica,sans-serif">Notes</FONT></H3>
      
<font face="arial,helvetica,sans-serif">
    <P>Standard NURBS curve definition. Curve is inserted into the currently opened 
    segment. 

    <p>The parametric start and end points are defined to range from zero to one, which is different
    from some solid modelers.  Solid modelling kernels typically parameterize their curves
    with respect to the given knot vector.

    <p>Any fields that can be left unspecified have default values: 0 for <em>start</em>, 1 for <em>end</em>,
    linearly increasing values for <em>knot</em>  (i.e. [0,1,2,3,4,5,6,7...]) and uniform <em>weights</em> 
    (i.e. [1,1,1,1,1...]).

</font></P>
      <P><FONT face=arial,helvetica,sans-serif>            

	<FONT color=#0000a0 face="arial,helvetica,sans-serif"><strong>Option flags:</strong></FONT></P><p>
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		<TD height=21 width=50>0001</TD>
		<TD height=21 width=390>Weights are specified</TD>
		</TR>
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		<td WIDTH=50 HEIGHT=21>0002</td>
		<td WIDTH=390 HEIGHT=21>Knots are specified</td>
		</tr>
	<tr>
		<td WIDTH=50 HEIGHT=21>0004</td>
		<td WIDTH=390 HEIGHT=21>Start is specified</td>
		</tr>
	<tr>
		<td WIDTH=50 HEIGHT=21>0008</td>
		<td WIDTH=390 HEIGHT=21>End is specified</td>
		</tr>
	</table>
	<p></FONT>
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